Background: The relationship between non-reassuring fetal heart rate (FHR) pattern, acidemia at birth and neonatal morbidity remains unclear. Our aim was to compare low versus high pH cord blood infants of women detected with a Category II FHR pattern for which the impact is unclear.
Methods: A prospective study of 185 low-risk pregnant women in labor at > 370/7 weeks of gestation with a singleton fetus was conducted at a single center. Category II trace was defined by the presence of tachycardia or bradycardia, variable and late decelerations, marked variability at least 30 minutes in the 120 minutes prior to delivery. The primary outcome included the need for resuscitation and Neonatal Intensive Care Unit (NICU) admission. The cohort was also stratified into three categories according to admission to NICU and pH threshold ([i] umbilical artery blood pH < 7.15 and admitted; [ii] pH > 7.15 and admitted; [iii] not admitted).
Results: 23% (43/185) of infants of women detected with Category II FHR pattern needed NICU admission. Category II FHR pattern was associated with low pH at birth, and the need for resuscitation was more frequent among infants in the lower pH group (73% vs. 10%, p < 0.05). Indices of right (tricuspid annular plane systolic excursion [TAPSE]: 7.3 ± 0.9 mm) and left ventricular performance (fractional shortening: 31% ± 8.9%, transmitral E’/A’ 0.9 ± 0.3) were low compared to normative data for healthy infants. CK, CK-MB, and left-to-right/bidirectional shunts at PFO and PDA were higher overall at 72 hours of age.
Conclusions: Category II FHR is associated with resuscitation at birth, NICU admission, and length of hospitalization.